small indefinite amount vs small indefinite quantity

small indefinite amount and small indefinite quantity both are nouns.

Word	Noun	Adjective	Verb	Adverb
small indefinite amount	Yes	No	No	No
small indefinite quantity	Yes	No	No	No

As nouns, small indefinite amount and small indefinite quantity are synonyms defined as:

small indefinite amount and small indefinite quantity: an indefinite quantity that is below average size or magnitude

small indefinite amount (noun)	small indefinite quantity (noun)
an indefinite quantity that is below average size or magnitude	an indefinite quantity that is below average size or magnitude